The preservation, protection and maintenance of color in foods and beverages are frequently difficult. Natural pigments either originally contained in the food or added thereto may well deteriorate because of exposure to light, air or extremes of temperature or because they interact with constituents in the product. These changes may occur readily or over long periods of time, and may result in fading, darkening or change in hue, any of which can affect acceptability.
When foods do not contain natural or inherent color of sufficient quality or stability, the use of color additives serves several important functions. Added color makes food more visually appealing and helps emphasize or identify flavors normally associated with a particular food. Greater uniformity of appearance is obtained by adding color to correct natural variations resulting from storage, processing, packaging and distribution.
It is well-known that many of the synthetic colors, generally called FD&C colors, have broad utility in food products, including those prepared with low pH aqueous solutions. For example, U.S. Pat. No. 3,511,667 teaches that almost all of the FD&C colors are water soluble in their acid form and consequently in their acid form dissolve at a low pH in aqueous systems. As a notable exception, however, the reference states that FD&C Red No. 3 can normally be employed only in neutral and alkaline aqueous mediums in addition to its particular utility in fatty materials. Thus, this reference recognizes the difficulties art workers have encountered when attempting to formulate clear, acidic food products, much less clear aqueous acid beverages, employing FD&C Red No. 3 as a colorant.
Red No. 3, also known as erythrosine, is a xanthene-type synthetic coal tar derived synthetic color. Chemically, it can be defined as the disodium salt of tetraiodofluorescein. It is an extremely bright pink/red color, is insoluble in acids and exhibits a very strong fluorencence and strong staining properties. It has been used in aqueous food products, but has heretofore been generally restricted to systems with a pH of above about 4.5. The insolubility is probably due to the fact that it contains a carboxylic group which is predominantly in the un-ionized form below pH 4.5.
The problems associated with employing Red No. 3 in acid beverages were also recognized in U.S. Pat. No. 3,425,841. However, this patent does disclose that a small amount of Red No. 3 (approximately 8 parts per million) can be added to a cloudy pineapple/grapefruit juice blend with a pH as low as 3.1 to impart a pink tint to the juice.
Another prior art attempt to color food products with Red No. 3 includes jet milling the dye. In this manner a dispersion of FD&C Red No. 3 at low pH's may be improved by micro-pulverizing the dry color pieces in a unit such as a Micron-Master.sup.(.TM.) Jet Pulverizer. These units operate by impacting one particle dirven at high velocity by jet of air or steam against other particles of the same material. Milling by such a process reduces the particle size of the colorant to the 1-10 micron range. The resultant product, while not soluble in water, is more dispersible than its un-milled counterpart. However, the stability of the so-called solution is relatively short. In the case of jet milled FD&C No. 3 placed in a beverage with a pH of less than 4.5, the color will precipitate within an hour.
Unlike FD&C No. 3, some natural, oil soluble colors such as turmeric, annatto and paprika are insensitive to pH and insoluble in water at any pH. Some of these oil based colors are, however, commercially available in water dispersible form. These colors are not soluble in water but form dispersions which, within a short period of time, typically less than 1 hour, will begin to precipitate. Oleoresin forms are available wherein the color is standardized or stabilized with polysorbate 80. Polysorbates generally are known for their use in foods as emulsifiers, solubilizing agents and dispersing agents. Specifically, they are used as emulsifiers in ice cream, frozen custard, ice milk, icings, fillings and toppings. They are used as solubilizing and dispersing agents in pickles, pickle products, fat soluble vitamin and vitamin/mineral preparations, and as dispersing agents in gelatin desserts and gelatin dessert mixes.
Other emulsifying agents or solvents such as propylene glycol, di-glycerides and various vegetable oils and fats are also compatible with natural oil based food colorants to render them oil dispersible. Two manufacturers who produce this class of color are McCormick & Company, Industrial Flavor Division, Hunt Valley, Maryland and Chr. Hansen's Laboratory, Milwaukee, Wisconsin. Liquid colors prepared in this manner are insensitive to pH since the entire composition is oil based and is, therefore, at best, only slightly soluble in water. This class of color is also available in dry form wherein the color is spray dried on a carrier, typically gum Arabic, along with a stabilizer such as polysorbate 80 to yield a dry, oil-dispersible, freeflowing product. Typical uses for turmeric are sausage cases, margarine, shortenings and other fatty foods. Paprika and annatto are used to color cheese and fatty foods. These oil-based colors, however, are unstable in aqueous systems and are not employed in water-based beverages or dry mixes which are reconstituted with water.
Similarly with these natural colors, the carotenoid dyes are insoluble in water and insensitive to pH, but additionally, they have only limited solubility in oils. German Pat. No. 2,411,529 relates to the preparation of liquid carotenoid dyes which are dispersible in water. The disclosed process includes heating a mixture of polysorbate selected from the group consisting of polysorbate 60 and polysorbate 80, monoglycerides of low molecular weight, saturated coconut acids and saturated fractions of coconut oil triglycerides to a temperature of 100 to 120.degree. C, and then adding the desired carotenoid to the mixture.
Notwithstanding the above techniques for dealing with the pH insensitive colors and the long standing need existing for an acid soluble form of Red No. 3, the prior art has heretofore been unable to solve the problems associated with the use of FD&C Red No. 3 in low pH systems. Since there is no known method of stabilizing Red No. 3 in low pH soluble food systems which are relatively clean and free from precipitation or haze and particularly those derived from dry beverage mixes, it would be highly desirable if a simple method were devised which would allow the use of Red No. 3 in such systems.